Proton Single-Energy Bragg-Peak FLASH Using Clinical Systems Can Achieve IMPT-Equivalent Plan Quality for Breast and Prostate Cancers

PURPOSE/OBJECTIVE(S)

Most current proton FLASH-RT studies focus on transmission proton techniques. In this study, we propose a novel method for achieving FLASH dose rate in hypofractionated proton radiotherapy using the Bragg peak of a single-energy proton beam. The dosimetric characteristics using this novel technique for proton pencil beam scanning (PBS) stereotactic body radiation therapy (SBRT) of prostate and breast cancers were first investigated based on the clinically available cyclotron beam parameters.

MATERIALS/METHODS

This novel approach uses the distal tracking technique that enables PBS Bragg-peak of the highest proton energy to adapt to the target distally. Positioning of the Bragg peak at different depths is achieved using a universal range shifter and range compensator. To investigate the feasibility of this approach, we developed an in-house treatment planning platform for intensity-modulated proton therapy (IMPT) delivery and performed dosimetric studies on prostate and breast SBRT cases previously treated with conventional proton PBS technique. FLASH plans were generated using a similar clinical beam arrangement to deliver 40 Gy (RBE) in 5 fractions. Dose metrics were compared between the clinical and FLASH plans. Dose-rate volume histograms (DRVH) were also calculated to investigate the 40 Gy/s coverage (V40 Gy/s) of organs-at-risk (OARs) for FLASH plans.

RESULTS

The distal tracking can precisely stop the Bragg peak at the target distal edge, and Bragg peak plans achieved tumor coverage and dose conformality equivalent to IMPT plans. The clinical IMPT plans yielded slightly superior target dose uniformity -CTV Dmax of FLASH plans was 10% higher for prostate and 2% higher for breast. There was no significant difference between the clinical and FLASH plans in dose metrics for major OARs, including rectum, large bowel, heart, and lung. Higher maximal doses to femoral heads (∼2 Gy) and urethra (∼6 Gy) were observed in prostate FLASH plans than in the clinical plans but were still within clinically accepted dose limits. The V40 Gy/s for OARs were >90% for prostate FLASH plans and >76.5% for breast FLASH plans.

CONCLUSION

The proposed single-energy Bragg-peak FLASH technique eliminates exit dose associated with transmission proton FLASH and can still yield comparable plan quality and OAR sparing while preserve sufficient FLASH dose rate coverage for prostate and breast proton SBRT. This study demonstrates the potential application of Bragg peaks for highly conformal FLASH-RT using clinical cyclotron systems to treat prostate and breast cancer patients, which moves towards clinical application.

Pencil Beam Scanning Proton Stereotactic Body Radiation Therapy (SBRT): A Robust Single Institution Experience

PURPOSE/OBJECTIVE(S)

To describe the feasibility of treating a complex and diverse group of patients using pencil beam scanning (PBS) proton stereotactic body radiation therapy (SBRT: 5 or fewer fractions, with a fraction size of at least 5 Gy).

MATERIALS/METHODS

Our center treats on average 105-120 PBS proton treatments daily, of which 9.5% of treatment courses are proton SBRT. Statistics of disease sites, treatment planning parameters (target volume, prescriptions, number of fields, SFO vs. MFO), and treatment efficiencies (scheduled time slots, actual treatment time) are presented for 305 consecutive SBRT patients receiving 1507 fractions in the past three years. Thermoplastic masks or Vacuum-lock bags are used to immobilize SBRT patients and index the patients' treatment position. Imaging guidance of orthogonal kV images and volumetric cone-beam CT is routinely used for patient setup.

RESULTS

SBRT patients are grouped based on the target locations: pelvis (31%), liver (17%), thoracic (13%), spine (8%), abdominal (8%), brain (7%), non-spine bone (7%), ocular (6%), and head and neck (2%). Only 112 patients (37%) were receiving their 1st RT course, whereas 113 (37%) had one prior in-field RT course, and 80 (26%) had multiple prior in-field RT courses. The median [IQR] target volume was 65.4 [29.3, 168] cc (range: 0.3-2475 cc). 72% of cases were planned with SFO and 28% with MFO. On average, 3.76 fields (range: 2 to 12) were planned for each treatment. 44% of the treatments were planned with three or fewer fields, and 10% received more than five fields, most of which involved repainting for moving targets. Over 97% of treatments were delivered in 5 fractions, with ∼3% delivered in 3 fractions. The median [IQR] prescription per treatment was 8 [7, 10] Gy (range: 5-18 Gy per treatment). 85% (84%) of the SBRT treatments were scheduled (delivered) in a 45-minute or shorter slot, and 6% (7%) of treatments were scheduled (delivered) in over a one-hour slot, most commonly for multiple isocenter treatments. 93% of treatments were delivered within 15 minutes of the planned treatment time or shorter. Deep-inspiration breath-hold (DIBH) was applied to 45% of liver SBRT cases, with the remaining 55% planned on 4D CT with (14%) or without (86%) abdominal compression. DIBH was applied in 13% of lung SBRT cases. The application of other motion mitigation approaches, such as volumetric repainting, was determined by the target motion amplitude and whether the patient could tolerate DIBH.

CONCLUSION

In the most diverse and largest proton SBRT experience delivered in the world over the past 3 years, over 300 patients were treated, demonstrating the feasibility and efficiency of delivering proton SBRT in a very busy center. The planning and treatment parameter statistics reported serve as a helpful reference for the proton community.

Practice Patterns and Disparities of Fractionation Schemes for Post-Mastectomy Comprehensive Nodal Irradiation

PURPOSE/OBJECTIVE(S)

Hypofractionated (HF) radiotherapy is the established standard of care for whole breast irradiation and is being investigated for comprehensive nodal irradiation, but appropriate patient selection for the latter is currently undefined. This study aims to report national practice patterns and patient selection for HF comprehensive nodal irradiation compared to conventional fractionation (CF). The hypothesis is that the rate of HF for comprehensive nodal irradiation in breast cancer has been increasing over time and is more likely to be offered to disparate demographic populations.

MATERIALS/METHODS

We queried the National Cancer Database and identified 128,693 patients who received comprehensive nodal irradiation between 2008-2016 in the United States. No patient who underwent lumpectomy received HF nodal irradiation; therefore, only post-mastectomy patients were included in this study. After the exclusion, 29,053 post-mastectomy patients with adjuvant comprehensive nodal irradiation remained. A multivariable binomial regression analysis between HF and CF patients was performed.

RESULTS

Of the patients identified, 1,910 received HF (6.57%), and 27,143 received CF (93.43%) radiotherapy. All patients had locally advanced breast cancer treated with mastectomy, lymph node dissection, adjuvant radiation, and +/- chemotherapy. The median dose in the HF group was 4,256 cGy in 16 fractions, and in the CF group was 6,040 cGy in 33 fractions. HF rate grew from 3.56% in 2004-2007, 5.29% in 2008-2011, 7.42% in 2012-2013, and 12.05% in 2014-2016. HF was favored in older patients (median age 66 vs. 51, OR = 1.16, 95% Cl 1.11-1.22) and those who lived in suburban or rural regions compared to urban or metropolitan regions (OR = 9.48, 95% CI 1.17-76.9). However, there was no correlation when distance from treatment site was evaluated as a continuous variable. A "boost" dose was used in only 10.58% of HF patients compared to 54.6% of CF patients (OR = 0.17, 95% Cl 0.14-0.21). Chemotherapy was delivered in 36.91% of HF patients compared to 78.14% of CF patients (OR = 0.77, 95% Cl 0.59-0.99). There were no statistically significant correlates of either fractionation scheme for breast laterality, stage, grade, or receptor status. Notably, other than population density and age, demographic factors including race, Hispanic origin, insurance type, median income, and education level demonstrated no correlation with radiation fractionation scheme.

CONCLUSION

HF for comprehensive nodal irradiation in breast cancer is still uncommon but growing in popularity. Currently, HF is more likely to be used in elderly patients and lower population density centers and less likely to be used in those determined to benefit from receipt of a boost or chemotherapy.

Treatment of Thymoma and Thymic Carcinoma with Proton Beam Therapy: Outcomes from the Proton Collaborative Group Prospective Registry

PURPOSE/OBJECTIVE(S)

Given the generally long natural history of thymic malignancies, proton beam therapy (PBT) is advocated to minimize the risk of long-term toxicities to mediastinal organs. Adverse events (AE) and long-term clinical outcomes for this population have not been well-characterized.

MATERIALS/METHODS

The Proton Collaborative Group registry (NCT01255748), a multi-institutional prospective database of academic and community proton centers in the US, was queried for patients with thymomas and thymic carcinomas treated with PBT. Patients with recurrent/metastatic disease, non-thymic histology, received either prior or palliative radiotherapy (dose < 40 Gy RBE) were excluded. Overall survival (OS) and local control (LC) were estimated using Kaplan-Meier methods.

RESULTS

A total of 97 patients were identified in the PCG registry. After applying relevant exclusion criteria, 70 patients from 12 proton centers treated from 2011-2021 were included for analysis. Median follow-up length was 16 months. Median age was 58.5 years (IQR 46-63), and 60% were female. 81.4% had a diagnosis of thymoma, and 18.6% thymic carcinoma. 59 patients underwent surgical resection. 11 were treated with definitive PBT, of which 5 received concurrent chemotherapy. Median dose was 54 Gy RBE (range 41.4 - 70 Gy RBE), median number of fractions was 30 (range 21 - 38). 73.4% received pencil beam scanning and 23% uniform scanning PBT. Treatment was overall well-tolerated: a single patient developed grade 4 pneumonitis. Grade 3 AEs were seen in 3 patients - dyspnea, anorexia, and heart failure. Highest grade toxicity experienced was grade 2 for 47.1% and grade 1 for 42.9% of patients. 3-year overall survival (OS) was 82.6% for the entire cohort. 3-year OS was 94% for resected/adjuvant cohort and 35.6% in the non-surgical/definitive cohort. 3-year local control (LC) was 91.7% for the entire cohort. By surgery/margin status, 3-year LC was 96.8% in patients with close or negative margins (a single failure in a patient with close margins), whereas 3-year LC was 55.1% for patients with positive margins/unresectable disease.

CONCLUSION

Thymic malignancies treated with PBT appear to have favorable outcomes, especially in the adjuvant setting, in this cohort representing the largest series of such patients.

Prospective Evaluation of Patient-Reported Outcomes of Invisible Ink Tattoos for the Delivery of External Beam Radiation Therapy: The PREFER Trial

PURPOSE/OBJECTIVE(S)

Invisible ink tattoos allow for setup accuracy while avoiding the cosmetic permanence of visible ink tattoos. The goal of this trial was to evaluate patient-reported preference for the use of invisible ink tattoos in a radiation oncology clinic.

MATERIALS/METHODS

In an IRB-approved, prospective, feasibility trial, patients at a single institution receiving pencil beam scanning proton therapy to the thorax, abdomen, or pelvis underwent invisible ink tattoo-based treatment setup. Patient preference surveys comparing visible and invisible ink tattoos were completed prior to simulation (17 questions), immediately following simulation (5 questions), and at the end of treatment (18 questions), with preference scored on a 5-point Likert scale from strongly disagree to strongly agree, and cosmesis scored on a 4-point Likert scale of excellent-good-fair-poor. Differences in distributions were examined using Wilcoxon rank-sum tests, Fisher's exact tests, or chi-square tests, where statistical significance was considered at p<0.05.

RESULTS

Of 107 patients screened, 102 were enrolled and 94 completed all surveys. Mean age was 55.0 years, and 58.5% were female. Most patients were white (79.1%) and non-Hispanic (92.6%). Patients most commonly had breast (34.0%), prostate (16.0%), and lung (9.6%) cancer. An average of 5 (range 3-8) invisible ink tattoos were placed per patient. Overall, 75.5% of patients reported that they would prefer to receive invisible tattoos vs. visible tattoos, and 88.3% rated the overall cosmetic outcome of invisible ink tattoo marks as excellent or good. Compared to males, females were more willing to travel farther from their home in order to avoid receiving visible tattoos (45.4% vs. 23.1%, p = 0.035) and would pay additional money to avoid receiving visible tattoos (34.5% vs. 5.1%, p = 0.002). Patients who had previously received any tattoo (cosmetic or visible RT tattoos) were more satisfied with the appearance of their invisible ink tattoos compared to those who had never previously received tattoos (82.9% vs. 61.5%, p = 0.022). Patients receiving definitive intent RT were more satisfied with the appearance of the tattoos compared to those receiving palliative intent RT (67.1% vs. 38.9%, p = 0.011). Patients with at least a college education were less satisfied with the appearance of tattoos compared to those without a college education (67.0% vs. 95.0% p = 0.018).

CONCLUSION

These findings demonstrate stronger avoidance of visible tattoos and patient preference for invisible tattoos. The standard incorporation of invisible ink tattoos for patient setup should be strongly considered.

A Dosimetric Assessment of Sexual Organ Sparing Proton Radiotherapy in Female Pelvic Cancer Patients

PURPOSE/OBJECTIVE(S)

Optimizing treatment techniques for female patients undergoing curative treatment for pelvic cancers requires incorporating the goals of maximizing cure while maintaining quality of life. Optimizing treatment to maintain sexual quality of life has received little attention in female patients despite the presence of and toxicity risks to functional anatomic organs and their associated neurovasculature, including the bulboclitoris, vagina, and ovaries. Recent dosimetric data without employing sexual organ sparing suggest that mean VMAT dose to the bulboclitoris in low rectal cancer is around 3300 cGy, and in anal cancer, mean dose is around 2000 cGy to the external genitalia and 4500-5000 cGy to the bulboclitoris, all of which would be expected to result in clinically significant toxicity. Therefore, investigation of the avoidance of these important organs is needed and we hypothesize that proton techniques may achieve greater sparing than photon techniques.

MATERIALS/METHODS

In this study, we dosimetrically compare proton- vs. photon-based techniques in sparing functional sexual organs. The cohort consisted of four consecutive female pelvic cancer cases that had received 5000 cGy or greater. All cases were re-planned with VMAT and protons while optimizing dose to functional sexual organs and maintaining target coverage. Sexual organ structures assessed include the genitalia, vagina, ovaries, bulboclitoris and internal pudendal arteries. Given the small number of patients included in this demonstration study, statistical tests were not performed.

RESULTS

MRI was required to appropriately delineate soft tissue. In all cases, dosimetric sparing of sexual organs was improved with proton therapy without compromising target coverage. Mean doses were marginally decreased for structures within the PTV, while structures such as the bulboclitoris were spared substantially. Mean dose to the external genitalia was low with sparing using both VMAT (Median [IQR] (cGy): 852 [811, 1090]) and Proton techniques (Median [IQR] (cGy): 39.4 [11.9, 78.5]). Similarly, mean dose with sparing to the external genitalia was lower than would be expected without sparing, using both VMAT and Proton techniques (Median (IQR) Dmean (cGy) VMAT 3100 [2890, 3580] vs. Proton 1530 [1100, 2090]), with protons demonstrating greater sparing. In one case of a sacral chordoma, ovaries were substantially spared to below ablative thresholds (Dmean (cGy) VMAT 3598.8 and 3548.0 vs Proton 34.1 and 103.3).

CONCLUSION

Magnetic resonance imaging at simulation combined with proton radiotherapy for female sexual organ sparing may provide a technically feasible route to more equitable sexual outcomes for female patients. These results will guide future studies to optimize proton treatment techniques for female sexual organ sparing for future trials.

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at sqrt[s]=510 GeV in p[over →]+p[over →] Collisions

We present measurements of the cross section and double-helicity asymmetry A_{LL} of direct-photon production in p[over →]+p[over →] collisions at sqrt[s]=510  GeV. The measurements have been performed at midrapidity (|η|<0.25) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at sqrt[s]=510  GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range 0.02<x<0.08, with direct sensitivity to the sign of the gluon contribution.

Heart failure with improved ejection fraction (HFimpEF) in patients treated with sacubitril/valsartan (SV)

Introduction

Several studies demonstrated that patients with improvement of left ventricular ejection fraction (LVEF) and symptoms had good prognosis in heart failure with reduced ejection fraction (HFrEF). Based on these results, new classification of HF according to LVEF was currently proposed. Sacubitril/valsartan (SV) is recommended as one of the first-line therapy of HFrEF patients. SV reduced hospitalization for HF and cardiovascular mortality compared to enalapril in PARADIGM-HF trial. However, it is unclear that patients with improvement of LVEF also have better prognosis compared to patients without LVEF improvement among patients treated with SV.

Purpose

We aimed to evaluate the clinical characteristics and outcomes of heart failure with improved ejection fraction (HFimpEF) in heart failure with reduced ejection fraction (HFrEF) patients treated with SV.

Methods

We analyzed 230 patients with HFrEF taking SV in a multicenter retrospective cohort (RECORD-SV registry) from 2017 to 2019. Enrolled 230 patients were performed baseline and 1-year follow-up echocardiography. Based on 2 echocardiographic results, we defined “HFimpEF” as HF with a baseline LVEF ≤40%, ≥10% increase from baseline LVEF and a follow-up measurement of LVEF &gt;40%. Others were defined as “Persistent HFrEF”. We analyzed and compared clinical characteristics and outcomes between two groups. Primary endpoint was a composite outcome of all-cause death and hospitalization for HF (HHF).

Results

From 230 patients, 65 patients with HFimpEF and 165 patients with Persistent HFrEF were analyzed. The median follow-up duration was 557 days (interquartile range 364 to 727 days). Patients with HFimpEF had a higher prevalence of female gender (50.8% vs. 30.3%) and de novo HF (44.6% vs. 21.2%). There were no significant differences for age, etiology (ischemic vs. non-ischemic), diabetes, atrial fibrillation, hypertension, and HF medications including SV dose between two groups. Patients with HFimpEF showed lower rate of all-cause death or HHF as a primary endpoint compared to patients with persistent HFrEF (6.2% vs. 22.4%; IPTW adjusted HR 0.24; 95% CI 0.13–0.46; p&lt;0.001) (Table 1). It was also shown that HFimpEF patients had a reduced risk of primary endpoint in the Kaplan-Meier curves compared with persistent HFrEF (Log-rank p=0.045) (Figure 1). We demonstrated that Non-prior MI (adjusted OR 7.29; 95% CI 1.50–35.36; p=0.014) and de novo HF (adjusted OR 4.33; 95% CI 1.70–11.04; p=0.002) were independent prognostic factors of HFimpEF in HFrEF patients treated with SV.

Conclusions

HFimpEF patients had better clinical outcomes compared to those with persistent HFrEF in HFrEF patients treated with SV. Non-prior MI and de novo HF were independent predictors of HFimpEF in patients treated with SV.

Funding Acknowledgement

Type of funding sources: None.

Probing Gluon Spin-Momentum Correlations in Transversely Polarized Protons through Midrapidity Isolated Direct Photons in p^{↑}+p Collisions at sqrt[s]=200 GeV

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in p^{↑}+p collisions at sqrt[s]=200  GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a 50-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

Live Vaccinia Virus-Coated Microneedle Array Patches for Smallpox Vaccination and Stockpiling

Although smallpox has been eradicated globally, the potential use of the smallpox virus in bioterrorism indicates the importance of stockpiling smallpox vaccines. Considering the advantages of microneedle-based vaccination over conventional needle injections, in this study, we examined the feasibility of microneedle-based smallpox vaccination as an alternative approach for stockpiling smallpox vaccines. We prepared polylactic acid (PLA) microneedle array patches by micromolding and loaded a second-generation smallpox vaccine on the microneedle tips via dip coating. We evaluated the effect of excipients and drying conditions on vaccine stability in vitro and examined immune responses in female BALB/c mice by measuring neutralizing antibodies and interferon (IFN)-γ-secreting cells. Approximately 40% of the virus titer was reduced during the vaccine-coating process, with or without excipients. At -20 °C, the smallpox vaccine coated on the microneedles was stable up to 6 months. Compared to natural evaporation, vacuum drying was more efficient in improving the smallpox vaccine stability. Microneedle-based vaccination of the mice elicited neutralizing antibodies beginning 3 weeks after immunization; the levels were maintained for 12 weeks. It significantly increased IFN-γ-secreting cells 12 weeks after priming, indicating the induction of cellular immune responses. The smallpox-vaccine-coated microneedles could serve as an alternative delivery system for vaccination and stockpiling.

An unusual anatomical variant of the left phrenic nerve encircling the transverse cervical artery

During educational dissection of cadavers, we encountered anatomical variability of the left phrenic nerve (PN). In this cadaver, nerve fibres from C3 and C4 descended and crossed behind the transverse cervical artery (TCA), a branch of the thyrocervical trunk, at the level of the anterior scalene muscle. On the other hand, nerve fibres from C5 descended obliquely above the TCA and then joined the fibres from C3-C4 on the medial side of the anterior scalene muscle to form the PN. To our knowledge, the encircling of the TCA by the left PN in the neck has not yet been reported and may pose a potential risk for nerve compression during movement of the neck. We discuss several types of anatomical variants of the PN and the associated risk during thorax and neck dissection procedures.

Patchless administration of canine influenza vaccine on dog's ear using insertion-responsive microneedles (IRMN) without removal of hair and its in vivo efficacy evaluation

Microneedles provide the advantages of convenience and compliance by avoiding the pain and fear of needles that animals often experience. Insertion-responsive microneedles (IRMN) were used for administration to a hairy dog without removing the dog's hair. Canine H3N2 vaccine was administered with IRMN attached to the dog's ears ex vivo and the conventional microneedle system (MN) was administered for 15 min to compare puncture performance and delivery efficiency. The vaccine was also administered to compare antibody formation using IRMN with the use of intramuscular injection. The veterinarian observed the behavior of the dog during the course of the administration and compared the response to IRMN with that of intramuscular administration. The tips of IRMN were separated from the base and delivered into the hairy skin successfully. Puncture performance of IRMN were the same as that of coated microneedles (95%), but delivery efficiency of IRMN were 95% compared to less than 1% for coated microneedles. The H3N2 vaccine inoculated into the dog's ears showed the same antibody formation as the intramuscular injection. The dog appeared to be more comfortable with IRMN administration compared to syringe administration. IRMN are the first microneedle system to deliver a canine vaccine successfully into a hairy dog without removal of the dog's hair. The use of IRMN can provide both convenience and compliance for both the dog and the owner.

Erratum: Evolution of π^{0} Suppression in Au+Au Collisions from sqrt[s_{NN}]=39 to 200 GeV [Phys. Rev. Lett. 109, 152301 (2012)]

This corrects the article DOI: 10.1103/PhysRevLett.109.152301.

Nuclear Dependence of the Transverse Single-Spin Asymmetry in the Production of Charged Hadrons at Forward Rapidity in Polarized p+p, p+Al, and p+Au Collisions at sqrt[s_{NN}]=200 GeV

We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively charged hadrons in polarized p^{↑}+p, p^{↑}+Al, and p^{↑}+Au collisions at sqrt[s_{NN}]=200  GeV. The measurements have been performed at forward rapidity (1.4<η<2.4) over the range of transverse momentum (1.8<p_{T}<7.0  GeV/c) and Feynman x (0.1<x_{F}<0.2). We observed positive asymmetries for positively charged hadrons in p^{↑}+p collisions, and significantly reduced asymmetries in p^{↑}+A collisions. These results reveal a nuclear dependence of TSSAs for charged-hadron production in a regime where perturbative techniques are applicable. These results provide new opportunities to use p^{↑}+A collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSAs as a new handle in studying small-system collisions.

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3  GeV/c) direct-photon yields from Au+Au collisions at sqrt[s_{NN}]=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrt[s_{NN}]=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1  GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5  GeV/c), but when results from different collision energies are compared, an additional sqrt[s_{NN}]-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

Pseudorapidity Dependence of Particle Production and Elliptic Flow in Asymmetric Nuclear Collisions of p+Al, p+Au, d+Au, and ^{3}He+Au at sqrt[s_{NN}]=200 GeV

Asymmetric nuclear collisions of p+Al, p+Au, d+Au, and ^{3}He+Au at sqrt[s_{NN}]=200  GeV provide an excellent laboratory for understanding particle production, as well as exploring interactions among these particles after their initial creation in the collision. We present measurements of charged hadron production dN_{ch}/dη in all such collision systems over a broad pseudorapidity range and as a function of collision multiplicity. A simple wounded quark model is remarkably successful at describing the full data set. We also measure the elliptic flow v_{2} over a similarly broad pseudorapidity range. These measurements provide key constraints on models of particle emission and their translation into flow.

Measurements of Multiparticle Correlations in d+Au Collisions at 200, 62.4, 39, and 19.6 GeV and p+Au Collisions at 200 GeV and Implications for Collective Behavior

Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of two-, four-, and six-particle angular correlations in d+Au collisions at sqrt[s_{NN}]=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrt[s_{NN}]=200  GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at sqrt[s_{NN}]=200 GeV

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

Immediate separation of microneedle tips from base array during skin insertion for instantaneous drug delivery

Insertion-responsive microneedles (IRMNs) have been developed that can enable instantaneous drug delivery without applying patches through immediate tip separation upon insertion.

Alpha-fetoprotein is a significant prognostic factor for gastric cancer: Results from a propensity score matching analysis after curative resection

BACKGROUND

Prognosis of alpha-fetoprotein positive gastric cancer (AFPP-GC) remains elusive so far due to disparities in cohort size and baseline characteristics in previous studies. A propensity score matching (PSM) analysis as well as multivariable model was performed for unbiased evaluation of the outcome in AFPGC.

METHODS

Among 3034 gastric cancer patients who underwent curative gastric cancer surgery (R0, M0) at the National Cancer Center, Korea between 2002 and 2007, we identified 97 patients being positive for AFP either by elevation of serum-AFP levels >10 μg/L or by immunohistochemical staining. Due to marked disparities in baseline characteristics and cohort size, propensity-score-matching was performed which matched 87 AFPP-GC patients to the same number of AFP-negative gastric cancer (AFPN-GC) patients. Baseline characteristics were compared using χ²-test. Survival curves were compared using the Kaplan-Meier-method and multivariable regression analysis was performed to evaluate the effect of AFP-positivity while adjusting the effects of confounding variables.

RESULTS

AFPP-GC and AFPN-GC patients revealed marked disparities in patient cohorts. After PSM, groups were balanced for age, sex, tumor size, BMI, tumor location, grade of differentiation, presence of lymphatic vessel infiltration (LVI), Lauren histologic type and stage distribution. In multivariable regression analysis of the PSM-groups, only AFP-positivity and pathologic stage were predictive for overall survival (HR 2.98, CI 95% {1.7-5.1}, p < 0.0001). Five-year-survival rates were significantly worse for AFPP-GC patients (57.9% vs. 76.1%, p = 0.014). Recurrence was significantly more frequent in AFPP-GC patients (p = 0.003).

CONCLUSION

AFP can be considered as an independent negative predictor of overall and recurrence-free survival in patients with gastric cancer.

Centrality-Dependent Modification of Jet-Production Rates in Deuteron-Gold Collisions at √[s(NN)]=200 GeV

Jet production rates are measured in p+p and d+Au collisions at sqrt[s_{NN}]=200  GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the R=0.3 anti-k_{t} algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum (p_{T}) spectra are corrected for the detector response. Spectra are reported for jets with 12<p_{T}<50  GeV/c, within a pseudorapidity acceptance of |η|<0.3. The nuclear-modification factor (R_{dAu}) values for 0%-100% d+Au events are found to be consistent with unity, constraining the role of initial state effects on jet production. However, the centrality-selected R_{dAu} values and central-to-peripheral ratios (R_{CP}) show large, p_{T}-dependent deviations from unity, challenging the conventional models that relate hard-process rates and soft-particle production in collisions involving nuclei.

Measurements of Elliptic and Triangular Flow in High-Multiplicity 3He+Au Collisions at √(s(NN))=200 GeV

We present the first measurement of elliptic (v(2)) and triangular (v(3)) flow in high-multiplicity (3)He+Au collisions at √(s(NN))=200  GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in (3)He+Au and in p+p collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the (3)He+Au system. The collective behavior is quantified in terms of elliptic v(2) and triangular v(3) anisotropy coefficients measured with respect to their corresponding event planes. The v(2) values are comparable to those previously measured in d+Au collisions at the same nucleon-nucleon center-of-mass energy. Comparisons with various theoretical predictions are made, including to models where the hot spots created by the impact of the three (3)He nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.

Measurement of Long-Range Angular Correlation and Quadrupole Anisotropy of Pions and (Anti)Protons in Central d+Au Collisions at sqrt[s_{NN}]=200 GeV

We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central d+Au and minimum bias p+p collisions at sqrt[s_{NN}]=200 GeV. The charged hadron is measured at midrapidity |η|<0.35, and the energy is measured at large rapidity (-3.7<η<-3.1, Au-going direction). An enhanced near-side angular correlation across |Δη|>2.75 is observed in d+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength v_{2} for inclusive charged hadrons at midrapidity up to p_{T}=4.5 GeV/c. We also present the measurement of v_{2} for identified π^{±} and (anti)protons in central d+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calculations and measurements from p+Pb at sqrt[s_{NN}]=5.02 TeV. The magnitude of the mass ordering in d+Au is found to be smaller than that in p+Pb collisions, which may indicate smaller radial flow in lower energy d+Au collisions.

Cold-nuclear-matter effects on heavy-quark production at forward and backward rapidity in d + Au collisions at √sNN = 200 GeV

The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1 < p(T) < 6  GeV/c at forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p + p collisions at √sNN = 200  GeV. In central d+Au collisions, relative to the yield in p + p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-p(T) broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d + Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter.

Azimuthal-angle dependence of charged-pion-interferometry measurements with respect to second- and third-order event planes in Au+Au collisions at √[S(NN)]=200 GeV

Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au+Au collisions at sqrt[s_{NN}]=200  GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow.

Long-term metformin use reduces gastric cancer risk in type 2 diabetics without insulin treatment: a nationwide cohort study

BACKGROUND

Metformin use has been associated with a decreased incidence and mortality of various cancers.

AIM

To evaluate the association between metformin use and gastric cancer.

METHODS

We randomly selected 100 000 type 2 diabetic patients from the 2004 Korean National Health Insurance claim database, and assessed gastric cancer incidence among 39 989 patients (aged 30-97 years) who were regularly treated with anti-diabetic drugs and followed-up from 2004 to 2010. In total, 26 690 patients had used metformin out of 32 978 diabetics who had not regularly used insulin (insulin non-users), and 5855 patients had used metformin out of 7011 regular insulin users.

RESULTS

Patients who used metformin showed a lower incidence of gastric cancer than those who did not use metformin, in insulin non-users (P = 0.047, log-rank test). However, in patients on regular insulin, there was no difference of gastric cancer incidence according to metformin use. In insulin non-users, the adjusted hazard ratio (AHR) for metformin use was 0.73 (95% confidential interval [CI], 0.53-1.01) with borderline statistical significance (P = 0.059). Duration of metformin use was associated with the reduction in gastric cancer risk (AHR, 0.88; 95% CI 0.81-0.96, P = 0.003), especially in patients who used metformin for more than 3 years (AHR, 0.57; 95% CI, 0.37-0.87; P = 0.009).

CONCLUSION

Metformin use >3 years in type 2 diabetics who do not use insulin is associated with a significantly reduced gastric cancer risk.

Quadrupole anisotropy in dihadron azimuthal correlations in central d+Au collisions at √(s(NN))=200 GeV

The PHENIX collaboration at the Relativistic Heavy Ion Collider (RHIC) reports measurements of azimuthal dihadron correlations near midrapidity in d+Au collisions at √(s(NN))=200 GeV. These measurements complement recent analyses by experiments at the Large Hadron Collider (LHC) involving central p+Pb collisions at √(s(NN))=5.02 TeV, which have indicated strong anisotropic long-range correlations in angular distributions of hadron pairs. The origin of these anisotropies is currently unknown. Various competing explanations include parton saturation and hydrodynamic flow. We observe qualitatively similar, but larger, anisotropies in d+Au collisions at RHIC compared to those seen in p+Pb collisions at the LHC. The larger extracted v2 values in d+Au are consistent with expectations from hydrodynamic calculations owing to the larger expected initial-state eccentricity compared with that from p+Pb collisions. When both are divided by an estimate of the initial-state eccentricity the scaled anisotropies follow a common trend with multiplicity that may extend to heavy ion data at RHIC and the LHC, where the anisotropies are widely thought to arise from hydrodynamic flow.

Nuclear modification of ψ', χc, and J/ψ production in d+Au collisions at sqrt[s(NN)]=200 GeV

We present results for three charmonia states (ψ', χc, and J/ψ) in d+Au collisions at |y|<0.35 and sqrt[s(NN)]=200  GeV. We find that the modification of the ψ' yield relative to that of the J/ψ scales approximately with charged particle multiplicity at midrapidity across p+A, d+Au, and A+A results from the Super Proton Synchrotron and the Relativistic Heavy Ion Collider. In large-impact-parameter collisions we observe a similar suppression for the ψ' and J/ψ, while in small-impact-parameter collisions the more weakly bound ψ' is more strongly suppressed. Owing to the short time spent traversing the Au nucleus, the larger ψ' suppression in central events is not explained by an increase of the nuclear absorption owing to meson formation time effects.

Staging of intestinal- and diffuse-type gastric cancers with the OLGA and OLGIM staging systems

BACKGROUND

Operative link on gastritis assessment (OLGA) and Operative link on gastric intestinal metaplasia assessment (OLGIM) staging systems have been proposed for gastric cancer (GC) risk estimation.

AIM

To validate the OLGA and OLGIM staging systems in a region with high risk of GC.

METHODS

This retrospective study included 474 GC patients and age- and sex-matched health screening control persons in a cancer centre hospital. We classified gastritis patterns according to the OLGA and OLGIM systems using the histological database that a pathologist prospectively evaluated using the updated Sydney system. GC risk according to the OLGA and OLGIM stages was evaluated using logistic regression analysis.

RESULTS

More GC patients had OLGA stages III-IV (46.2%) than controls (26.6%, P < 0.001), particularly among patients with intestinal-type GCs (62.2%) compared with diffuse-type GCs (30.9%). OLGA stages III and IV were significantly associated with increased risk of GC [odds ratios (ORs), 2.09; P = 0.008 and 2.04; P = 0.014 respectively] in multivariate analysis. The association was more significant for intestinal-type (ORs, 4.76; P = 0.001 and 4.19; P = 0.002 respectively), but not diffuse-type GC. OLGIM stages from I to IV were significantly associated with increased risk of both intestinal-type (ORs, 3.64, 5.15, 7.89 and 13.20 respectively) and diffuse-type GC (ORs, 1.84, 2.59, 5.08 and 6.32 respectively) with a significantly increasing trend.

CONCLUSION

As high OLGA and OLGIM stages are independent risk factors for gastric cancer, the staging systems may be useful for risk assessment in high-risk regions, especially for intestinal-type gastric cancer.

Randomised clinical trial: the effects of Helicobacter pylori eradication on glandular atrophy and intestinal metaplasia after subtotal gastrectomy for gastric cancer

BACKGROUND

Helicobacter pylori eradication is recommended for early gastric cancer (GC) patients after resection.

AIM

To evaluate whether H. pylori eradication improves glandular atrophy and intestinal metaplasia (IM) in GC patients undergoing subtotal gastrectomy.

METHODS

This randomised, double-blind trial was performed in tertiary care setting. Distal GC patients with H. pylori infection were randomised to receive proton pump inhibitor-based triple therapy or placebo. The histology was evaluated using the updated Sydney system before and at 36 months after surgery. The endpoints were the comparison of atrophy and IM score changes between the allocated groups and according to final H. pylori status.

RESULTS

Overall, 190 patients were randomised to the treatment and placebo groups. For lesser curvature of the corpus, mean atrophy and IM scores did not differ between the treatment and placebo groups. However, the H. pylori-eradicated patients had significantly lower mean scores than the H. pylori-persistent patients regarding atrophy (0.55 ± 0.95 vs. 1.05 ± 1.10 respectively; P = 0.0046) and IM (0.66 ± 0.99 vs. 1.05 ± 1.16 respectively; P = 0.0284). The percentage change from baseline was more marked in the H. pylori-negative than in the H. pylori-positive groups (-58.6% vs. -11.0% for atrophy and -60.5% vs. -35.6% for IM respectively). For greater curvature, mean atrophy score was lower in the H. pylori-negative group than in the H. pylori-positive group (0.14 ± 0.50 vs. 0.41 ± 0.75 respectively; P = 0.0281). The percentage change was -36.4% vs. 86.3%.

CONCLUSION

Helicobacter pylori eradication in GC patients is beneficial, as reflected by lower scores of atrophy and IM at 36 months after subtotal gastrectomy. (ClinicalTrials.gov number, NCT01002443).

Medium modification of jet fragmentation in Au+Au collisions at √[s(NN)]=200 GeV measured in direct photon-hadron correlations

The jet fragmentation function is measured with direct photon-hadron correlations in p+p and Au+Au collisions at √[s(NN)]=200 GeV. The p(T) of the photon is an excellent approximation to the initial p(T) of the jet and the ratio z(T)=p(T)(h)/p(T)(γ) is used as a proxy for the jet fragmentation function. A statistical subtraction is used to extract the direct photon-hadron yields in Au+Au collisions while a photon isolation cut is applied in p+p. I(AA), the ratio of hadron yield opposite the photon in Au+Au to that in p+p, indicates modification of the jet fragmentation function. Suppression, most likely due to energy loss in the medium, is seen at high z(T). The associated hadron yield at low z(T) is enhanced at large angles. Such a trend is expected from redistribution of the lost energy into increased production of low-momentum particles.

Cold-nuclear-matter effects on heavy-quark production in d+Au collisions at sqrt[S(NN)]=200 GeV

The PHENIX experiment has measured electrons and positrons at midrapidity from the decays of hadrons containing charm and bottom quarks produced in d+Au and p+p collisions at sqrt[S(NN)]=200 GeV in the transverse-momentum range 0.85 ≤ p(T)(e) ≤ 8.5 GeV/c. In central d+Au collisions, the nuclear modification factor R(dA) at 1.5<p(T)<5 GeV/c displays evidence of enhancement of these electrons, relative to those produced in p+p collisions, and shows that the mass-dependent Cronin enhancement observed at the Relativistic Heavy Ion Collider extends to the heavy D meson family. A comparison with the neutral-pion data suggests that the difference in cold-nuclear-matter effects on light- and heavy-flavor mesons could contribute to the observed differences between the π(0) and heavy-flavor-electron nuclear modification factors R(AA).

Evolution of π(0) suppression in Au+Au collisions from √(s(NN))=39 to 200 GeV

Neutral-pion π(0) spectra were measured at midrapidity (|y|<0.35) in Au+Au collisions at √(s(NN))=39 and 62.4 GeV and compared with earlier measurements at 200 GeV in a transverse-momentum range of 1<p(T)<10 GeV/c. The high-p(T) tail is well described by a power law in all cases, and the powers decrease significantly with decreasing center-of-mass energy. The change of powers is very similar to that observed in the corresponding spectra for p+p collisions. The nuclear modification factors (R(AA)) show significant suppression, with a distinct energy, centrality, and p(T) dependence. Above p(T)=7 GeV/c, R(AA) is similar for √(s(NN))=62.4 and 200 GeV at all centralities. Perturbative-quantum-chromodynamics calculations that describe R(AA) well at 200 GeV fail to describe the 39 GeV data, raising the possibility that, for the same p(T) region, the relative importance of initial-state effects and soft processes increases at lower energies. The p(T) range where π(0) spectra in central Au+Au collisions have the same power as in p+p collisions is ≈5 and 7 GeV/c for √(s(NN))=200 and 62.4 GeV, respectively. For the √(s(NN))=39 GeV data, it is not clear whether such a region is reached, and the x(T) dependence of the x(T)-scaling power-law exponent is very different from that observed in the √(s(NN))=62 and 200 GeV data, providing further evidence that initial-state effects and soft processes mask the in-medium suppression of hard-scattered partons to higher p(T) as the collision energy decreases.

Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV

We report the measurement of direct photons at midrapidity in Au+Au collisions at √(s(NN))=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/c<p(T)<22 GeV/c, using a statistical method to subtract decay photons from the inclusive photon sample. The direct photon nuclear modification factor R(AA) was calculated as a function of p(T) for different Au+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R(AA) was found to be consistent with unity for all centralities over the entire measured p(T) range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R(AA) from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.

Observation of direct-photon collective flow in Au + Au collisions at √s(NN)] = 200 GeV

The second Fourier component v(2) of the azimuthal anisotropy with respect to the reaction plane is measured for direct photons at midrapidity and transverse momentum (p(T)) of 1-12 GeV/c in Au + Au collisions at √s(NN)] = 200 GeV. Previous measurements of this quantity for hadrons with p(T) < 6 GeV/c indicate that the medium behaves like a nearly perfect fluid, while for p(T) > 6 GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for p(T) > 4 GeV/c the anisotropy for direct photons is consistent with zero, which is as expected if the dominant source of direct photons is initial hard scattering. However, in the p(T) < 4 GeV/c region dominated by thermal photons, we find a substantial direct-photon v(2) comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region underpredict the observed v(2).

Effect of chemotherapy on the outcome of self-expandable metallic stents in gastric cancer patients with malignant outlet obstruction

BACKGROUND AND STUDY AIM

Chemotherapy has been suggested to affect the outcome of pyloric stent placement. This study aimed to investigate the association between the response to chemotherapy and pyloric stent outcome.

PATIENTS AND METHODS

Data from 113 patients with inoperable gastric cancer who received chemotherapy after pyloric stent placement at the National Cancer Center hospital were analyzed retrospectively. Chemotherapy response was assessed using the Response Evaluation Criteria in Solid Tumors. A Cox proportional hazards model was used to evaluate the effect of chemotherapy response on the complications of stents.

RESULTS

The stent migration rate was 15.9% (18/113) and the re-stenosis rate was 30.1% (34/113). The response rates to chemotherapy were higher in the first-line group than in the salvage chemotherapy group (second-line or more) (44.8% [26/58] vs. 3.6% [2/55], respectively; P < 0.001). The proportion of patients with long time-to-progression (> 8 weeks) was also higher in the first-line than the salvage chemotherapy group (81.0% [47 /58] vs. 61.8% [34 /55], respectively; P = 0.036). Although, the response to chemotherapy was not associated with stent migration or re-stenosis, a long time-to-progression (adjusted hazard ratio [aHR] = 0.29, 95% confidence interval [CI] 0.13-0.67) and first-line chemotherapy (aHR = 0.45, 95%CI 0.22-0.93) were protective factors against re-stenosis in the multivariate analysis. In patients who received first-line chemotherapy, the median duration of patency of covered and uncovered stents was 20 weeks (95%CI 11-29) and 33 weeks (95 %CI 18-48), respectively (P = 0.317).

CONCLUSIONS

A long time-to-progression and first-line chemotherapy were significant protective factors against re-stenosis. In chemotherapy-naïve gastric cancer patients with pyloric obstruction, placement of an uncovered stent followed by chemotherapy can be considered to increase stent patency.

The influence of hospital volume and surgical treatment delay on long-term survival after cancer surgery

BACKGROUND

We conducted a population-based retrospective cohort study to investigate the influence of hospital volume, delay of surgery, and both together on the long-term survival of postoperative cancer patients.

METHODS

Using information from the Korea Central Cancer Registry from 2001 through 2005 and the National Health Insurance claim database, we determined survival for 147 682 patients who underwent definitive surgery for any of six cancers.

RESULTS

Regardless of cancer site, surgical patients in low- to medium-volume hospitals showed significantly worse survival [adjusted hazard ratio (aHR) = 1.36-1.86] than those in high-volume hospitals in multivariable analyses. Among the latter, treatment delays > 1 month were not associated with worse survival for stomach, colon, pancreatic, or lung cancer but were for rectal [aHR = 1.28; 95% confidence interval (CI), 1.17-1.40] and breast (aHR = 1.59; 95% CI, 1.37-1.84) cancer. For patients in low- to medium-volume hospitals, treatment delay was associated with worse survival for all types of cancer (aHR = 1.78-3.81).

CONCLUSION

Our findings suggest that the effect of hospital volume and surgical treatment delay on overall survival of cancer patients should be considered in formulating or revising national health policy.

Aspirin use and bleeding risk after endoscopic submucosal dissection in patients with gastric neoplasms

BACKGROUND AND STUDY AIM

The risk of bleeding after endoscopic submucosal dissection (ESD) in patients with early gastric neoplasms who do not discontinue aspirin for the procedure has not been established. We aimed to investigate whether post-ESD gastric bleeding is increased in patients who take aspirin.

PATIENTS AND METHODS

Patients who underwent ESD for early gastric neoplasms at the National Cancer Center Hospital, Korea, between November 2008 and January 2011 were enrolled. The risk of post-ESD bleeding was evaluated using Poisson regression analysis.

RESULTS

We categorized 514 patients into three groups according to aspirin intake at the time of the procedure: patients who never used aspirin (n=439), patients who interrupted aspirin use for 7 days or more (n=56), and patients who continuously used aspirin (n=19). Post-ESD bleeding occurred in 4.1% (21/514) overall, and was more frequent in continuous aspirin users (4/19 [21.1%]) than in those who never used aspirin (15/439 [3.4%]) (P=0.006) and those with interrupted aspirin use (2/56 [3.6%]) (P=0.033). Multivariate analysis showed that use of aspirin by itself was associated with post-ESD bleeding (relative risk [RR] 4.49; 95% confidence interval [95%CI] 1.09-18.38). The resumption of clopidogrel combined with aspirin use (RR 26.71, 95%CI 7.09-100.53), and increased iatrogenic ulcer size (RR 1.52, 95%CI 1.14-2.02), were significantly associated with post-ESD bleeding.

CONCLUSIONS

Continuous aspirin use increases the risk of bleeding after gastric ESD. Aspirin use should be stopped in patients with a low risk for thromboembolic disease to minimize bleeding complications.

Measurements of higher order flow harmonics in Au+Au collisions at √s(NN)=200 GeV

Flow coefficients ν(n) for n=2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at √s(NN)=200 GeV, are measured relative to event planes Ψ(n), determined at large rapidity. We report ν(n) as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The ν(n) are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio η/s.

Suppression of back-to-back hadron pairs at forward rapidity in d+Au collisions at √s(NN)=200 GeV

Back-to-back hadron pair yields in d+Au and p+p collisions at √s(NN)=200 GeV were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity |η|<0.35 and the associated hadron at forward rapidity (deuteron direction, 3.0<η<3.8). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in d+Au collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to p+p collisions. The kinematics of these pairs is expected to probe partons in the Au nucleus with a low fraction x of the nucleon momenta, where the gluon densities rise sharply. The observed suppression as a function of nuclear thickness, p(T), and η points to cold nuclear matter effects arising at high parton densities.

Cold nuclear matter effects on J/ψ yields as a function of rapidity and nuclear geometry in d+A collisions at sqrt[s(NN)]=200 GeV

We present measurements of J/ψ yields in d+Au collisions at sqrt[s(NN)]=200  GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/ψ rapidity (-2.2<y<2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. In order to remove model dependent systematic uncertainties we also compare the data to a simple geometric model. The forward rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

Comparison of surgical performance and short-term clinical outcomes between laparoscopic and robotic surgery in distal gastric cancer

AIMS

The authors aimed to compare the surgical performance and the short-term clinical outcomes of robotic assisted laparoscopic distal gastrectomy (RADG) with laparoscopy-assisted distal gastrectomy (LADG) in distal gastric cancer patients.

METHOD

From April 2009 to August 2010, 62 patients underwent LADG and 30 patients underwent RADG for preoperative stage I distal gastric cancer by one surgeon at the National Cancer Center, Korea. Surgical performance was measured using lymph node (LN) dissection time and number of retrieved LNs, which were viewed as surrogates of technical ease and oncologic quality.

RESULTS

In clinicopathologic characteristics, mean age, depth of invasion and stage were significantly different between the LADG and RADG group. Mean dissection time at each LN station was greater in the RADG group, but no significant intergroup difference was found for numbers of retrieved LNs. Furthermore, proximal resection margins were smaller, and hospital costs were higher in the RADG group. In terms of the RADG learning curve, mean LN dissection time was smaller in the late RADG group (n = 15) than in the early RADG group (n = 15) for 4sb/4d, 5, 7-12a stations, but numbers of retrieved LNs per station were similar.

CONCLUSION

With the exception of operating time and cost, the numbers of retrieved LNs and the short-term clinical outcomes of RADG were found to be comparable to those of LADG, despite the surgeon's familiarity with LADG and lack of RADG experience. Further studies are needed to evaluate objectively ergonomic comfort and to quantify the patient benefits conferred by robotic surgery.

Risk of high-grade dysplasia or carcinoma in gastric biopsy-proven low-grade dysplasia: an analysis using the Vienna classification

BACKGROUND AND AIMS

Therapeutic guidelines have not yet been established for low-grade gastric adenomas/dysplasias (LGD), which have a low risk of progression to high-grade adenomas/dysplasias (HGD) or to invasive carcinomas. This study aimed to evaluate risk factors for HGD/carcinoma that indicate a need for resection in biopsy-proven LGD lesions.

PATIENTS AND METHODS

In total, 236 LGD lesions from 208 consecutive patients treated with endoscopic resection (ER) were retrospectively studied between 2004 and 2008. The Vienna classification was used for histological diagnosis. A generalized estimating equation (GEE) logistic regression model was used for multivariate analysis.

RESULTS

Among the 236 LGD lesions, the final pathology diagnosed 9 (3.8 %) as invasive carcinoma (category 5), 71 (30.1 %) as HGD (category 4), 148 (62.7 %) as LGD (category 3), and 8 (3.4 %) as negative/indefinite for dysplasia (category 1/2). Lesions ≥ 1 cm were classified as HGD/carcinoma in 39.4 % of patients (65/165). Multivariate analysis indicated that size of ≥ 1 cm (OR 1.93 [95 % CI, 1.06 - 3.52]), depressed morphology (OR 3.81 [95 % CI, 1.22 - 11.9]), and erythema (OR 2.49 [95 % CI, 1.31 - 4.72]) were significantly associated with HGD/carcinoma. The OR increased to 47.6 (95 % CI, 4.27 - 530.65) when the risk factors were all positive. The sensitivity and negative predictive value for ≥ 1 risk factors were 93.8 % and 90.9 %, respectively. As the number of risk factors of a lesion increased, the specificity and positive predictive value also increased.

CONCLUSIONS

Endoscopic resection can be recommended if a low-grade dysplastic lesion has at least one of the following risk factors: depressed morphology, surface erythema, or a size of 1 cm or greater. For lesions that have none of the three risk factors, follow-up endoscopy is recommended.

CYP2A6 and ERCC1 polymorphisms correlate with efficacy of S-1 plus cisplatin in metastatic gastric cancer patients

Background:

We evaluated the association between polymorphisms of cytochrome P450 2A6 (CYP2A6)/excision repair cross-complementation group 1 (ERCC1)/X-ray repair cross-complementing group 1(XRCC1) and treatment outcomes of metastatic gastric cancer (MGC) patients treated with S-1/cisplatin.

Methods:

Among MGC patients (n=108), who received S-1 (40 mg m⁻² b.i.d., days 1–14) and cisplatin (60 mg m⁻², day 1) every 3 weeks, we analysed the wild-type allele (W) and variants (V) of CYP2A6 (*4, *7, *9, *10), and the polymorphisms of ERCC1 (rs11615, rs3212986) and XRCC1 (rs25487).

Results:

Patients having fewer CYP2A6 variants had better response rates (W/W vs W/V other than *1/*4 vs V/V or *1/*4=66.7 vs 58.3 vs 32.3% P=0.008), time to progression (TTP) (7.2 vs 6.1 vs 3.5 months, P=0.021), and overall survival (23.2 vs 15.4 vs 12.0 months, P=0.004). ERCC1 19442C>A (rs3212986) was also associated with response rate (C/C, 46.7% vs C/A, 55.3% vs A/A, 87.5%) (P=0.048) and TTP (4.4 vs 7.6 vs 7.9 months) (P=0.012). Patients carrying both risk genotypes of CYP2A6 (V/V or 1/*4) and ERCC1 19442C>A (C/C) vs those carrying none showed an adjusted odds ratio of 0.113 (P=0.004) for response, and adjusted hazard ratios of 3.748 (P=0.0001) for TTP and 2.961 (P=0.006) for death.

Conclusion:

Polymorphisms of CYP2A6 and ERCC1 19442C>A correlated with the efficacy of S-1/cisplatin.

Cross section and parity-violating spin asymmetries of W± boson production in polarized p + p collisions at sqrt[s] = 500 GeV

Large parity-violating longitudinal single-spin asymmetries A(L)(e+) = -0.86(-0.14) (+0.30) and A(L)(e-) = 0.88(-0.71) (+0.12) are observed for inclusive high transverse momentum electrons and positrons in polarized p+p collisions at a center-of-mass energy of sqrt[s] = 500 GeV with the PHENIX detector at RHIC. These e± come mainly from the decay of W± and Z0 bosons, and their asymmetries directly demonstrate parity violation in the couplings of the W± to the light quarks. The observed electron and positron yields were used to estimate W± boson production cross sections for the e± channels of σ(pp → W+ X) × BR(W+ → e+ ν(e)) = 144.1 ± 21.2(stat)(-10.3) (+3.4) (syst) ± 21.6(norm)  pb, and σ(pp → W- X) × BR(W- → e- ν[over ¯](e)) = 31.7 ± 12.1(stat)(-8.2) (+10.1) (syst) ± 4.8(norm)  pb.